Peroxyacids have powerful oxidizing capacity which enables them to bleach household stains. These compounds also have powerful disinfectant and sanitizing properties which are generally superior to products which generate hydrogen peroxide when used under the same conditions.
While it would be greatly desirable to offer liquid compositions, particularly non-aqueous compositions, containing peroxyacids, the art teaches that there are special difficulties in preparing such compositions resulting in the decomposition of the peroxyacids.
U.S. Pat. No. 3,956,159 to Jones, for example, teaches that the reactive nature of peroxyacids presents special problems to the formulator upon storage of bleach in liquid media. The patent teaches the combination of a number of ingredients, including organic solvent, to stabilize the bleach. The reference fails to teach, however, how to incorporate a peroxyacid in a liquid composition which is based on surfactant instead of merely an organic solvent. Moreover, there is no suggestion that, if a non-aqueous liquid were used, even this would have to be specifically formulated to ensure stability. That is, even the peracids of the invention are not stable in all NAL formulations.
U.S. Pat. No. 4,783,278 to Sanderson et al. teaches that particulate potassium-4-sulphoperoxybenzoic acid is stable when dispersed in an organic liquid carrier phase comprising a nonionic surfactant. The amido and imido acids of the subject invention are neither taught nor suggested. Further, the reference teaches that other solid peracids dispersed in liquid nonionic surfactants result in instability, presumably because of the detrimental interaction between ethoxylated surfactants and peroxyacids (see column 1, lines 49-57). Thus, the art teaches away from the use of peroxyacids in non-aqueous liquids.
The detrimental interaction between peroxyacids and ethoxylated surfactants (e.g., in non-aqueous liquids) is further seen in U.S. Pat. No. 4,981,606 to Barnes where peroxyacid is stabilized only by using capped ethoxylated nonionic surfactant. The use of capped, alkoxylated nonionic is neither required nor preferred in the subject invention.
EP 484,095 mentions non-aqueous liquids (NALs) having stable solubilized imide peracids. By contrast, the peracids of the invention are substantially insoluble and such substantially insoluble peracids offer stability advantages over soluble peracids.
None of the above references teach or suggest non-aqueous liquid compositions containing peroxyacids of the invention. The aforementioned peroxyacids are substantially insoluble in non-aqueous liquids alone or in non-aqueous liquids containing other detergent solids. Further, none of the references teach or suggest that the peracids may only be stable if the builders and buffers are chosen according to specific criteria.
U.S. Ser. No. 07/970,344, now abandoned, which application is assigned to applicants' assignee, teaches non-aqueous liquids containing an inorganic persalt, particularly sodium percarbonate, and precursor compounds which are relatively insoluble in the non-aqueous, liquid phase. The application is concerned with the insolubility of the precursor and not with the insolubility of the specific peroxyacids of the invention. Moreover, carbonate salts are outside the scope of salts which should be used to ensure peracid stability according to the subject invention.
U.S. Pat. No. 5,268,003 to Coope et al. teaches the peroxyacids of the invention in aqueous liquids. At column 8, lines 20-21 there is mentioned, among a long list of product forms, that the peracids may be used in non-aqueous liquids. However, just because an acid may be insoluble in aqueous medium does not mean it will be insoluble in non-aqueous liquids or visa versa. Moreover, there is no teaching of how to stabilize the non-aqueous mediums since peroxyacids, including those of the invention, will not be stable in all non-aqueous mediums. They must be used under specified conditions. The lack of any teaching of conditions and the general teaching away in the art of using non-aqueous liquids for peracids strongly suggests that no-one of ordinary skill in the art would have known how to prepare the compositions of the invention based on the Coope et al. reference.
Accordingly, it is one object of the present invention to provide non-aqueous liquid compositions, particularly when the non-aqueous liquid phase is a liquid nonionic surfactant (preferably alkoxylated) or mixtures of such nonionic surfactants, wherein said compositions comprise amide or imide peroxyacids stable in the compositions. The non-aqueous liquid compositions preferably also comprise dispersed solids such as the insoluble peroxyacids of the invention and builder and buffer salts selected according to specific criteria defined by the invention.
It is a further object of the invention to provide peroxyacids which are substantially insoluble in the NALs such that their chemical stability is greatly enhanced.
Another object of the invention is to provide non-aqueous liquid compositions containing builder salts and buffer salts selected such that the salts, if used, are selected to minimize the detrimental effect on stability of the peroxyacid present in the liquid or actually enhance its stability.
Another object of the invention is to provide additional components to the compositions which may be used to further stabilize the peracids in the final compositions. Additional stabilizing components may include, for example, citric acid. Acid anionic surfactants (e.g., LAS), help stabilize citric acid containing compositions even further.